tree-optimization/115236 - more points-to *ANYTHING = x fixes

tree-optimization/115236 - more points-to *ANYTHING = x fixes

The stored-to ANYTHING handling has more holes, uncovered by treating
volatile accesses as ANYTHING.  We fail to properly build the
pred and succ graphs, in particular we may not elide direct nodes
from receiving from STOREDANYTHING.

	PR tree-optimization/115236
	* tree-ssa-structalias.cc (build_pred_graph): Properly
	handle *ANYTHING = X.
	(build_succ_graph): Likewise.  Do not elide direct nodes
	from receiving from STOREDANYTHING.

	* gcc.dg/pr115236.c: New testcase.